give someone a leg up
(to help someone achieve something)
- Speaking English gave me a leg up on getting a job.
- We’ve got some information that might give you a leg up.
(to hold your hands together for someone to use them as a step while climbing up onto something)
- Can you climb into this window if I give you a leg up?
have a leg up on
(have an advantage over)
- I want my children to have a leg up on everyone else.